650 nm to km conversion result above is displayed in three different forms: as a decimal (which could be rounded), in scientific notation (scientific form, standard index form or standard form in the United Kingdom) and as a fraction (exact result). Every display form has its own advantages and in different situations particular form is more convenient than another. For example usage of scientific notation when working with big numbers is recommended due to easier reading and comprehension. Usage of fractions is recommended when more precision is needed.
If we want to calculate how many Kilometers are 650 Nanometers we have to multiply 650 by 1 and divide the product by 1000000000000. So for 650 we have: (650 × 1) ÷ 1000000000000 = 650 ÷ 1000000000000 = 6.5E-10 Kilometers
So finally 650 nm = 0.00000000065 km